1. Field of the Invention
The present invention relates, generally, to a method and apparatus for flexible manufacturing and, more specifically, to a method and apparatus for flexible manufacturing a discrete curved part from feed stock.
2. Description of the Related Art
There are numerous parts, components, and sub-components that must be subjected to one or more manufacturing steps to impart a predetermined curvature thereto. These manufacturing steps typically require the use of hard tooling which can include multiple progressive dies, cold heading operations, tube bending operations as well as the need for other, associated components manufactured, for example, via plastic injection molding operations or the like. This tooling and related hardware as well as the batch type processing of such manufacturing operations ultimately have a significant impact on the cost of the manufactured part.
Curved parts, components, and sub-components are commonly employed in various automotive applications. As examples only, and not by way of limitation, such curved parts, components and subcomponents may be found in automotive seat frames, seat backs, brake lines, and other various structural elements which embody a bend in any way. One specific example includes automotive windshield wiper assemblies. More specifically, it is known to employ a single, elongated, curved, homogeneous strip that forms a spring xe2x80x9cbackbonexe2x80x9d of the windshield wiper assembly. Such windshield wiper assemblies are sometimes referred to as xe2x80x9cbeam bladexe2x80x9d type windshield wiper assemblies. The beam blade backbone is made from spring steel and may taper both in width and thickness from its center toward its free ends or tips. The backbone has a connecting formation at a central position for connection to a reciprocally driven arm. The arm applies a downward force and moves the blade assembly across the windshield. The backbone is curved along a plane that is similar to the plane of curvature as that defined by the windshield. A wiper element is secured to the backbone. The thickness and width of the backbone and its radius of curvature are preferably matched at every point along the length of the backbone so that the backbone will provide a force per unit length distribution in a longitudinal direction which increases toward both tips of the windshield wiper when the windshield wiper is in use, pressed downward intermediate its ends onto either a flat or complexly curved surface. Beam blade windshield wiper assemblies have the advantage of a lower profile as compared with tournament style wiper assemblies, consist of fewer parts and are considered to be aesthetically pleasing.
While such beam blade type windshield wiper assemblies have many desirable features and advantages, they can be difficult to manufacture and, due to the hard tooling required to shape, cut and curve the backbone, relatively expensive when compared with other conventional windshield wiper assemblies known in the related art.
However, the present invention overcomes these difficulties in the related art in a method and apparatus for flexible manufacturing a discrete curved part, such as the backbone of a beam blade windshield wiper assembly, from a feed stock. But, from the description that follows, those having ordinary skill in the art will appreciate that the method and apparatus of the present invention may be used to manufacture any discrete, curved part from a feed stock and that the invention is in no way limited to the particular application referred to above or described in greater detail below. Thus, the context of a beam blade type windshield wiper assembly as described herein is merely for example purposes to further illustrate the present invention, and not for any limiting purpose.
The present invention overcomes the deficiencies in the related art in a method and apparatus for flexible manufacturing a discrete curved product from a feed stock. The apparatus includes a source of heat that is adapted to impose a focused beam of heat on at least one surface of a work piece to cause the surface of the work piece to expand and thereby move in the general direction of the heat source and impart a predetermined radius of curvature to the work piece.
Applying the apparatus of the present invention in connection with the manufacture of a discrete curved backbone for a beam blade windshield wiper assembly from feed stock as disclosed in the specific example described herein, the apparatus includes a cold rolling mill that imparts a predetermined thickness to the work piece. The apparatus also includes a width profiling station that imparts a predetermined width to the work piece and a curvature forming and heat treat station. The curvature forming and heat treat station includes a first source of heat that is adapted to impose a focused beam of heat on at least one surface of the work piece. The beam of heat defines a major axis and a minor axis on the work piece. The major axis of the focused beam of heat is disposed substantially transverse to the relative movement of the work piece with respect to the beam of heat and imparts a predetermined radius of curvature about the major axis. In addition, the apparatus includes a cooler that cools the work piece after it has been heated by the first source of heat. A second source of heat is also employed to temper the work piece after it has been cooled.
A method of manufacturing a discrete curved product from a feed stock is also disclosed and includes the steps of providing a focused beam of heat on at least one surface of a work piece to cause the surface of the work piece to expand and thereby move in the general direction of the heat source and thereby impart a predetermined radius of curvature to the work piece.
As applied to the specific example of manufacturing a discrete curved backbone for a beam blade windshield wiper assembly from feed stock as described herein, the method includes the steps of imparting a predetermined thickness to the work piece and imparting a predetermined width to the work piece. The method also includes providing a first source of heat that is adapted to impose a focused beam of heat on at least one surface of the work piece wherein the beam of heat defines a major axis and a minor axis on the work piece and the major axis of the focused beam of heat is disposed substantially transverse to the relative movement of the work piece with respect to the beam of heat. The beam of heat imparts a predetermined radius of curvature about the major axis. In addition, the method includes the step of cooling the work piece after it has been heated by the first source of heat and tempering the work piece after it has been cooled.
Operator interface in a production line employing the method and apparatus of the present invention is minimal and consists, primarily, of monitoring the status of the production line and the product quality being produced, rather than control of the process. Ideally, the production line includes few or no hard tools, but rather, is primarily software controlled to allow changes and modifications to the end product""s xe2x80x9con the fly.xe2x80x9d Thus, as will be described in greater detail below, a production line employing the method and apparatus of the present invention is xe2x80x9cvirtually tooledxe2x80x9d and can produce any number of different parts without stopping or even slowing the manufacturing process. However, those having ordinary skill in the art will appreciate from the description that follows that, while the reduction in the use of hard tooling is an overall, general goal of the method and apparatus of the present invention, some hard tooling may still be employed in any given production line without deviating from the scope of the invention as defined in the appended claims.
Similarly, in the preferred embodiment contemplated by the inventors, the production line employing the method and apparatus of the present invention includes a digital signal processing computer having a neural network including a design database with predetermined manufacturing settings that control the overall process to produce the end product. Thus, the method and apparatus of the present invention offer numerous advantages over the traditionally hard-tooled production lines known in the related art. Most notably, these advantages include the ability to continuously flow process the working material while reducing or eliminating, as much as possible, the batching processes in the production of a part, component or sub-component. This advantage results in reduced costs, waste and labor expenses. The method and apparatus of the present invention also provides improvements in inventory turns and more efficient utilization of raw materials. Furthermore, the cost to manufacture and build a production line employing the method and apparatus of the present invention is less than the cost to tool a family of parts employed to manufacture products, such as windshield wiper assemblies, automotive seat frames, seat backs, brake lines, bent tubular products and other various structural elements that embody a bend in any way.